Drug Interactions between glatiramer and natalizumab

GENERALLY AVOID: The use of natalizumab with immunosuppressant, immunomodulating, or antineoplastic agents may increase the risk of infections including progressive multifocal leukoencephalopathy (PML), a severely disabling, potentially fatal opportunistic viral infection of the brain. In clinical trials, PML occurred in two of 1869 patients with multiple sclerosis treated with natalizumab for a median of 120 weeks and one of 1043 patients with Crohn's disease after eight doses of natalizumab. Both of the MS patients were receiving concomitant interferon beta therapy, and the third patient was immunocompromised due to recent treatment with azathioprine. However, the number of cases is too few and the number of patients treated too small to reliably conclude that the risk of PML is lower with natalizumab monotherapy.

MANAGEMENT: The safety and efficacy of natalizumab in combination with immunosuppressant, immunomodulating, antineoplastic or other myelosuppressive agents have not been evaluated. Patients receiving such agents should not be treated with natalizumab because of the possibility of increased risk of infections, including PML. However, short courses of corticosteroids may be given. All patients treated with natalizumab should be monitored closely and the drug discontinued immediately at the first sign or symptom suggestive of PML, although it is not known if early detection of PML and discontinuation of natalizumab will mitigate the disease.